Wind turbine blades have become increasingly longer of the years and may today have a length of 80 meters or more and may weigh tens of tons. The wind turbine blades are often manufactured as separate shell parts, e.g. as a pressure side shell part and a suction side shell part, which afterwards are assembled to form a complete aerodynamic blade shell. This can for instance be carried out via the mould parts, in which the shell parts are manufactured, or in a post-moulding station, e.g. provided with two cradles for receiving and carrying the blade shell parts.
The shell parts are assembled by gluing the shell parts at the leading edge and the trailing edge and require that one of the mould parts or cradles are turned over along with the carried blade shell part and aligned with the other mould part or cradle and other blade shell part. Therefore, the mould assembly or post-moulding station are provided with a turning system comprising a number of turning devices that allow a rotatable mould part or rotatable cradle to be turned over and closed against a fixed side mould part or fixed side cradle.
Due to the large size and weight of the blade shell parts and the moulds or cradles, the turning devices need to be able to provide a relative high moment of force during the turnover action. Further, it may be advantageous to design the turning system such that the required rotation height is limited in order to ensure that the mould part or cradle may be turned over without coming into contact with the ceiling of the manufacturing facility. The turning system may for instance be based on planet gears or hydraulics.
WO04043679 discloses a mould assembly, where the disclosed turning system is based on a gear system, such as a planet gear system.
WO08054088 discloses a mould assembly provided with a turning system that allows the rotating side mould to be rotated about two hinge axes in order to lower the overall rotation height during the turnover action.
WO12055395 similarly discloses a mould assembly provided with a pivoting system that allows the rotating side to be pivoted about a first rotary bearing and a second rotary bearing. At least the first rotary bearing is arranged in a distance from the standing surface of the stationary mould part.
EP2380720 also discloses a mould assembly where a rotating side mould may be rotated about two hinge axes in two rotation steps. During at least a part of the first rotation step, the rotating side mould undergoes a combined rotational and translational movement.
The known turning systems are rather bulky or expensive, since they are dimensioned with a large overhead for the required moment of force during the turnover action.